The present invention relates to a method of manufacturing a part for an optical fiber connector, and more specifically to a method of manufacturing a part generally called a ferrule that comprises some components and supports an optical fiber positioned in the center of the ferrule. The optical fiber connector connects optical fibers each having a perfect circular cross-section and a diameter of 0.125 mm by passing the optical fibers through a cylindrical-shaped tube to support them, so that the positions of cores positioned in the center of the optical fibers are accurately adjusted to each other.
A ferrule, which is conventionally one of parts for an optical fiber connector, has a shape shown in FIGS. 1(a) and 1(b), and the material of the ferrule principally includes one that uses zirconia ceramic. FIG. 1(a) shows a one-core type ferrule 1 with a cylindrical shape having a diameter of about 2 mm and a length of about 8 mm, and in the center of the circular shape of the ferrule 1 a perfect circular hole 2 of 0.126 mmxcfx86 is drilled. FIG. 1(b) shows a two-core type ferrule 1.
Meanwhile, the present inventor has been proposed in Japanese Patent Unexamined Publication No. Hei. 10-375372 a metallic ferrule made of nickel or the like by electroforming using a metallic or ceramic wire as a mother mold.
In the invention of the above-mentioned patent publication, a method comprising the steps of electroforming on a wire such as a metallic wire or the like used as a mother mold, and drawing the wire is a predominant method. However, since the method is not used for drawing the wire to a longer one, a drawing method has been proposed in which after sealing a wire 3 at regular intervals by electric insulators 4 such as vinyl tapes as shown in FIG. 2, electroforming is performed using the wire as a mother mold, then the insulators 4 are peeled to be in a state where the wire 3 extends from the electroformed portion 5 as shown in FIG. 3, and after setting the electroformed portion 5 on a drawing jig 6, the wire 3 clamped is drawn out.
More specifically, in the drawing method comprising the steps of using a wire such as a metallic wire or the like as a mother mold, and drawing the wire after electroforming on the mother mold wire, since the tensile strength of the wire is insufficient and the drawing resistance is high, the drawing is performed only to a length of about 30 to 100 mm of the length. To make the electroformed portion 5 into a rod as long as possible is very important for an improvement in productivity of the electroforming. As a result, the method using electric insulators was reluctantly adopted. However, the following problems arose.
When electroforming is performed applying an electrode from above using, for example, a stainless steel wire as a mother mold, the conductivity of the stainless steel wire is not good and electric current does not flow sufficiently to an electric insulator seal portion (portion not electroformed). Thus, there occurs the phenomenon that the upper and lower portions significantly tend to be thickened and thinned, respectively.
Thus, electric precipitation must be continued till a size of thinnest portion is changed to a desired size. As a result, there were wastes of electricity, time and electroformed metal.
Further, there were problems that since variations in the diameter of the obtained electroformed article were very large, a step of aligning the diameters of the electroformed articles by NC lathe working or the like must be added in the next machining step, or this aligning step tended to cause a failure such as an off-centered hole or the like.
On the other hand, since a step of sealing the wire with an electric insulator is carried out by a manual operation, a large amount of time is required, and if the electric insulator is not fixed sufficiently, a number of problems occur; the electric insulator such as a tape or the like shifts during the electroforming to a cause a failure and the like. Thus, conventional methods impede mass production in cost and quality.
Taking the above-mentioned problems into consideration, in a method of manufacturing a ferrule wherein electroforming is carried out using a wire such as a metallic wire or the like as a mother mold, and after drawing the wire, machining the obtained electroformed article, the object of the present invention is to provide a method by which an electroformed article having the longest possible length and a small variation in the size of diameters without the step of sealing an electric insulator.
To solve the above-described problems, the present invention adopts a method comprising the steps of electroforming a portion to be electroformed to form one elongated rod as shown in FIG. 5(a), cutting the circumferential surface of the rod to form grooves 7 thereon as shown in FIG. 5(b), breaking the groove portion and drawing the wire 3. Further, the method comprises machining the electroformed rod to adjust at least the length and size (diameter) of the rod.
It is noted that the rod may be machined to adjust the roundness and the linearity of the rod in addition to the length and diameter as required.